explain xkcd - User contributions [en]

Talk:2319: Large Number Formats

2020-06-13T02:20:05Z

172.68.215.76: /* Can someone explain the set theory notation? */

== Scientist avoiding rounding ==

Would love an explanation of the scientist avoiding rounding one. Would make sense to me with 2.525997..., but as 2.5997... I'm at a loss!

Truncating the number just before a digit less than 5 so that the final digit is not rounded up. (I do this all the time, and, I am a scientist.)

(The above was posted (anonymously?) seconds before I could get mine in, so here it is in the original format.)

This is probably completely irrelevant but it seems Randall made a small typo when trying to show a "Scientest trying to avoid rounding up."
I assume it should be 2.525997*10^13. It seems he left out a 5 and a 2 and I say such because whether he forgot the 52 or 25 is up for debate.

Relevant screenshot: [[https://i.imgur.com/NrvOivy.png]]

Also, if I'm just being completely daft and am missing something completely, please feel free to criticize me harshly and I'll go back to my little hideyhole. [[Special:Contributions/108.162.237.24|108.162.237.24]] 22:21, 12 June 2020 (UTC)

In reality, a scientist would probably say 6.416*10^13 cm. (Although possible counterpoint, this comic is really about the ''number'' 25,259,974,097,204, not the distance 25,259,974,097,204 inches.) [[Special:Contributions/172.69.33.207|172.69.33.207]] 22:47, 12 June 2020 (UTC)

Centimetres are not an SI unit. it would be 6.416*10^11 m [[Special:Contributions/172.68.255.14|172.68.255.14]] 01:56, 13 June 2020 (UTC)
I believe the "2.5997" was intentional, or at least I thought it was when reading it. At first I thought it was a typo, but Randall calls that number "Scientist ''trying'' to avoid rounding up" which makes me think Randall intentionally made that "mistake" as if the scientist had accidentally forgotten the first two digits (25) and used the remainder of the number (259974...), rounding it to "2.5997x10^13" [[User:Kirypto|Kirypto]] ([[User talk:Kirypto|talk]]) 23:03, 12 June 2020 (UTC)

As a (not so?) old British person, I approve. Let the Trillions come around later, when it's ''worth'' increasing the prefix to "level 3". Don't waste them on the more petty numbers. [[Special:Contributions/162.158.155.122|162.158.155.122]] 23:13, 12 June 2020 (UTC)

== "Engineering" notation omitted? ==

I find it somewhat strange that Randall doesn't offer '''25e12''' or any of those variants ('''25.259...*10^12'''). I feel like a lot of "non-normal" people would map billion to E12 instead of requiring a single digit to the left of the decimal point. shrug [[User:JohnHawkinson|JohnHawkinson]] ([[User talk:JohnHawkinson|talk]]) 23:09, 12 June 2020 (UTC)

==Actual scientist: ==
"What's an inch?" [[Special:Contributions/162.158.62.119|162.158.62.119]] 23:18, 12 June 2020 (UTC)
: The imaginary nano-scale multiple of the speed of light times Planck's constant. Which, dimensionally, would seem to be kg.m³/s²? [[Special:Contributions/162.158.154.73|162.158.154.73]] 00:15, 13 June 2020 (UTC)

As an article pointed out to me the other day that seemed obvious after it was said it's a non tarrif trade barrier used as American protectionism that doesn't get tarrifed back

== Can someone explain the set theory notation? ==
You can use only sets to construct the natural numbers, see https://en.wikipedia.org/wiki/Natural_number#Constructions_based_on_set_theory

2310: Great Attractor

2020-05-23T15:55:19Z

172.68.215.76: Fixed typo ("affect" should be "effect").

{{comic
| number = 2310
| date = May 22, 2020
| title = Great Attractor
| image = great_attractor.png
| titletext = Living in the southern hemisphere was nice because I could jump extra high, but I like it here too. Besides, if I ever want to move back, I can just curl up in a ball and wait!
}}

==Explanation==
{{incomplete|Created by a Greatly Attractive SpaceBOT. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

[[Cueball]] comments on the fact that as summer approaches, the sun rises earlier and sets later, a common topic of conversation, especially to complain that it is still light at times of day where you are used to it being dark out. [[Beret Guy]] comments that he fell off of the wall this morning, a seemingly unconnected topic.

People will often complain about falling out of bed as an indicator of having slept badly. The later sunset is often linked to worsened sleep [https://www.insider.com/why-its-hard-to-sleep-in-the-summer-2018-6]. However, Beret Guy didn't fall from the bed, he fell from the wall. While being able to figure out he's talking about his worsened sleep, Cueball is understandably confused, so Beret Guy clarifies.

Beret Guy is strongly affected by the {{w|Great Attractor}}, a large gravitational anomaly that influences the galaxies near it, but is difficult to observe directly. Beret Guy claims that the Great Attractor pulls on him unusually hard, which could be another one of his [[:Category:Strange powers of Beret Guy|strange powers]]. This attraction, while not overpowering the gravity of the earth, (as he states that he can only "Jump extra high" in the Title Text) affects his life greatly, such as allowing him to sleep on walls. While 'normal' people can probably (if uncomfortably) lie down on the top of a boundary wall, for Beret Guy this may, at various times, mean that he can lie on the vertical surface of any wall (external or internal) that is currently orientated in a fortuitous direction.

He fell off of the wall this morning due the Great Attractor being below him during daylight hours and on the horizon during night hours. Because the Day starts earlier in the summer, he fell unexpectedly.

He gives a short explanation of why the Great Attractor affects him, apparently caused by his bones existing in more dimensions than our normal 3 dimensions of space and 1 of time, and the motion of galaxies, which normally has no significant effect on a person.

Beret Guy then says that day-sliding season is near, due to the Great Attractor being at the horizon in the day, and offers to run errands for Cueball in the South, implying that he will be pulled towards the south during day-sliding season.

Beret Guy is not standing straight up during this comic, he has one knee slightly bent; and walks with a strange gait and movement lines around him. This is presumably due to the extra downwards force that the Great Attractor is currently exerting on him, so he has to exert more effort to hold himself upright and seems quite content, in the titletext, to entirely stop bracing himself against the pull by crouching into a more spherical shape and rolling down the 'sloping' ground to some place with lower net gravitational potential.

A prior example of an xkcd character with alternate gravitational susceptibility is [[417: The Man Who Fell Sideways]], where a consistent off-vertical pull somehow applies (rather than one linked to a spot on the stellar sphere) while other fictional examples of 'personalised' [https://wiki.lspace.org/mediawiki/Tethys gravitational] [https://wiki.lspace.org/mediawiki/Sally_Cambric susceptibilities] also exist, in various forms.

==Detail==
Some of the humor of the comic has to do with the immense differences in scale between Beret Guy and the Great Attractor.

In very round numbers our own Milky Way galaxy is 200,000 light years across. It is just one of several galaxies in something called the Local Group, which is around 10,000,000 light years across. And the Local Group is itself in something called the Local Supercluster (also called the Virgo Supercluster), around 110,000,000 light years across. Each galaxy, each group, and each supercluster is not just a chance alignment, but is a gravitationally coherent structure.

Something unpredicted (hence "anomalous") is going on with the galaxies in the Local Supercluster (including our own). These galaxies are indeed accelerating away from one another as seen by their red shift. Hubble's Law predicts the expansion should be uniformly proportional to their distance from Earth and from one another. But for the Local Supercluster something is restricting the expansion. That something is, as "viewed" from Earth, somewhere in the direction of the Southern Triangle constellation but 250,000,000 light years distant, and has (but only since 1988) been termed the Great Attractor. The Great Attractor can't conveniently be seen at visible wavelengths, because that direction is the so-called Zone of Avoidance: the area of the night sky obscured by our own Milky Way.

Boiling this all down: something a quarter of a billion light years away that makes an anomalous blip in the local rate of expansion of the universe, and whose existence astronomers deduce only by X-ray observations of stellar red-shift, has large-scale effects on everyday gravitational forces uniquely experienced by Beret Guy. OK, now you can smile.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:[Cueball and Beret Guy stand next to each other, talking.]
:Cueball: I can't believe it's still light out. It's 8:00 PM!
:Beret Guy: Seriously! This morning I fell off the wall.

:[In a frameless panel, Cueball and Beret Guy are still standing and talking. Beret Guy is gesturing to the right.]
:Cueball: Wait, why were you sleeping on the wall?
:Beret Guy: The Great Attractor is near the horizon at night right now.

:[A regular panel, zoomed in on Beret Guy, who is gesturing to the left.]
:Cueball (off screen): The Great Attractor?
:Beret Guy: Yeah! The space one.
:Beret Guy: It pulls on me extra hard. Doctors said it's something to do with galactic motion and how many dimensions my bones have.

:[Zoomed back out to show Cueball, standing still, and Beret Guy, who is sliding away to the right.]
:Beret Guy: This time of year, it's below us all day, so I stand vertically. But day-sliding season is near!
:Beret Guy: Let me know if you have any errands to run to the south!
:Beret Guy: ''Goodniiighttt''

{{comic discussion}}
[[Category: Comics featuring Cueball]]
[[Category: Comics featuring Beret Guy]]

Talk:2297: Use or Discard By

2020-04-23T06:29:38Z

172.68.215.76:

comics featuring expiration dates

This comic is definitely not related to the COVID-19 theme. Has Randall decided after 19 (or 20) comics to end his series? [[Special:Contributions/108.162.215.166|108.162.215.166]] 01:28, 23 April 2020 (UTC)
: I personally agree. However some will make the argument that all the people who stocked up on a lifetime supply will face "best by" issues in the next years. --[[Special:Contributions/172.68.215.76|172.68.215.76]] 06:29, 23 April 2020 (UTC)

She didn’t say it said “use by (some date)”. She just said it says “use by ..”. My interpretation is that it is so old the date has worn off. That happens to my nitroglycerin quite often. I think her interlocutor is saying, if the date has worn off or gotten illegibly smeared, assume it’s expired. —— OTOH the explanation given by the editors is funnier! [[Special:Contributions/108.162.216.232|108.162.216.232]] 05:08, 23 April 2020 (UTC)
:In the first panel she states that the guns (plural) are about to expire. So I guess they have bought 2 guns about the same time, from different vendors who handle this wording differently, but both flare guns have a visible expiry date in the close future. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 05:56, 23 April 2020 (UTC)